Abstract

The Beni Ider Flysch (Rif, Morocco) belongs to the mauretanien successions (internal units of the Maghrebian Flysch Domain) and represents the upper part of the Beni Ider Nappe, about 1800 m thick. Together with the Algeciras Flysch (Betic Cordillera, Spain), it represents the start of the detritic syn-orogenic sedimentation (beginning of the foredeep stage) in the Betic-Rifian Arc during Late Oligocene-Early Miocene. New interdisciplinary data from four sections measured in the Tetouan area provide a new provisional stratigraphic reconstruction of its succession and a sedimentological, petrographic and biostratigraphic characterization. The Ain-ech-Chouka and Oued Chekkour Sections (not older than Late Oligocene in age) show coarse- to very coarse-grained facies referred to proximal areas (probably base of slope) and seem to represent the lower portion of the stratigraphic succession. Their provenance, characterized by conspicuous supply from crystalline sources, is related to hypothetical plutonic and/or high grade metamorphic sources of the Internal Domain, although plutonic rock bodies have never been recognized in the higher tectonic units of the pre-Alpine Paleozoic basement (Ghomaride-Malaguide Units). The Oued Kalaa and Beni Harchan Sections [Late Oligocene?-Early Miocene (Aquitanian) in age], mainly composed of fine-grained facies with few coarse-grained episodes, show characters of basin plain environment, locally interested by distal turbidity currents of a fan fringe or by catastrophic megaflows. Their provenance is mainly from epimetamorphic and/or metasedimentary and carbonate rocks. These different provenances are undoubtedly linked to the paleogeographic and tectonic evolution of the source areas, reflecting a synsedimentary tectonic activity. The sedimentological characters and comparison with the previously studied Punta Fardioua outcrop, suggest the preliminary interpretation of a subsident basin which persists in a divergent setting, with marginal areas, base of slope, characterized by a low-efficiency turbidite system.